todo-http4s-doobie VS pfps-shopping-cart

In addition to the great work from Gabriel Volpe, there's the Scala Pet Store and a to-do app.

My only point, really, was that it isn’t just libraries that use the features and idioms of, e.g. the Typelevel ecosystem. For example, here is a “ToDo” app written with http4s, Doobie, and Circe. It reads like Typelevel library code—that is, it uses Typelevel ecosystem features and idioms, and no one familiar with them will have any trouble reading or modifying it.

Gabriel Volpe has a book that goes over just that using the typelevel stack. I highly recommend it: https://leanpub.com/pfp-scala

The only issue I had was how to put all this knowledge together. For that I bought Practical FP in scala by Gabriel Vlope, it's not for beginners, tho but takes you through a project with the latest typelevel stack. Here's the link. https://leanpub.com/pfp-scala.

This is a really good book https://leanpub.com/pfp-scala

If you want a solid understanding of FP and not just FP in Scala, I highly recommend installing GHCup and working through Haskell Programming From First Principles. Then I would work through Scala With Cats, Essential Effects, and Practical FP in Scala for how all of that maps onto Scala.

Practical FP in Scala

BTW for learning good application structure with Tagless Final I really recommend the book Practical FP in Scala and its work-along example application. That's where I stole the pattern above from.